Use of imaging sensors in vehicle imaging systems is common and known. Examples of such known systems are described in U.S. Pat. Nos. 5,949,331; 5,670,935 and/or 5,550,677, which are hereby incorporated herein by reference in their entireties.
Current testing of cameras (typically far field cameras) requires cameras to be tested at 8 meters or greater to check the focus of a camera at a distance that is representative of how the camera will function in a vehicle during normal driving conditions for the camera to function as designed. To test a camera at 8 meters or greater is difficult due to the size needed to test cameras at that distance. Many camera test and build facilities use a single intermediate optic system (see FIG. 2) to allow cameras to be tested at a closer distance. This intermediate optic makes it possible to test cameras in a more reasonable distance while still simulating the 8 meter distance.
The single intermediate optic does a good job correlating the center focus target (see FIG. 3, where this was measured at 99.2 percent), but the off axis targets (corner targets) correlation is not as good as the center focus (measured 79.5 percent, 89.1 percent, 77.1 percent, and 82.2 percent in the off axis four corners). This inconsistency in the off axis target focus can produce inconsistent data points in the off axis locations (corner targets).